If I keep the solar panels deployed, they will get damaged underwater.   No reason to keep them deployed, when the sun isn’t overhead and providing enough light.  I found four Photoresistors and connected one up to each of the slaves.   The current readings are sent to the master controller and displayed on LCD 0x24 and LCD 0x27.   pr.py is the main Pi file.   The Photo Resistors are on the Arduino devices.  I use the I2C connection to the Raspberry Pi to display the output on I2C Mini LCD screens.